1. Field of the Invention
This disclosure relates generally to power distribution systems and more particularly, to a method and apparatus for a circuit protection system providing multiple zone protective functions for zone protection throughout the system.
2. Description of the Prior Art
In power distribution systems, power is distributed to various loads and is typically divided into branch circuits, which supply power to specified loads. The branch circuits can also be connected to other power distribution equipment.
Due to the concern of an abnormal power condition in the system, i.e., a fault, it is known to provide circuit protective devices or power switching devices, e.g., circuit breakers, to protect the circuit. The circuit breakers seek to prevent or minimize damage and typically function automatically. The circuit breakers also seek to minimize the extent and duration of electrical service interruption in the event of a fault.
It is further known to open and close these circuit breakers based upon statically defined zones of protection within the configuration of the power distribution system. The contemporary protection system applies algorithms based upon electrical properties of these statically defined zones and clears the fault through the use of circuit breakers disposed within the statically defined zones of protection.
Such a contemporary system fails to account for changes to the state, topology or configuration of the power distribution system, such as power flow changes resulting from the opening or closing of circuit breakers. The failure of the protection system to adapt to the dynamics of the state of the power distribution system results in the application of incorrect algorithms and unwanted functions of power control devices based upon the erroneous, static state within the zone of protection. This increases the risk of damage to the system, such as failure to timely clear a fault. This also decreases the efficiency of the system, such as through untimely opening of circuit breakers and nuisance tripping, and can increase the extent and duration of electrical service interruption in the event of a fault.
Accordingly, there is a need for circuit protection systems incorporated into power distribution systems that decrease the risk of damage and increase efficiency of the power distribution system. There is a further need for protection systems that can vary the zones of protection and account for the changing state within the zones as the power distribution system changes. There is also a need for protection systems that provide optimized protection without sacrificing selectivity. There is additionally a need for computationally efficient techniques for performing complex zone functions on the varying zones of protection.